This application is related to the following pending applications being concurrently filed herewith and assigned to the assignee of the present invention:
This invention relates generally to air conditioning systems and, more particularly, to an air conditioning system which is integrated into the internal structure of a bus.
The conventional integrated bus air conditioning systems contain a condenser mounted in a luggage compartment and an evaporator mounted in the luggage compartment or in a separate compartment between the passenger compartment floor and the luggage compartment underneath the floor. The evaporator takes in the return air through a central return air duct mounted under the floor of the passenger compartment and blows the conditioned supply air into a side wall supply air duct. The condenser, which, is interconnected to the evaporator by a refrigerant tube, operates to condense the refrigerant in the circuit by way of the outside air that is brought in from and eventually discharged to the ambient air.
As part of the refrigeration circuit which is fluidly interconnected by tubing to both the evaporator and the condenser, an open drive reciprocating compressor is generally directly driven by a belt drive from the bus engine, such that the speed of the compressor is dependent on the speed of the drive engine. Accordingly, when the bus is at idle speed, for example, the capacity of the air conditioning system is substantially reduced. Further, the refrigeration connections between the compressor and the air conditioning system is generally expensive to install, difficult to service and somewhat unreliable because of possible refrigeration leaks and the need to maintain a compressor shaft seal.
Also typical of such a bus air conditioning system is the use of existing DC power to power the evaporator and condenser blower motors. Because of relatively low brush life for such motors, reliability and expense can also be a problem.
Also associated with the existing bus air conditioning systems is the problem of a component failure causing a complete loss of the air conditioning capacity. That is, with a single large unit as is now customary, failure of that unit such as, for example, a leaking hose causing loss of refrigerant, an electrical failure leading to inoperation of one of the components such as a fan, or a compressor failure, the entire unit is inoperable and no air conditioning can be provided to the unit. In such a situation, it would preferable if partial capacity could be maintained in order to provide a xe2x80x9climp homexe2x80x9d capability.
It is therefore an object of the present invention to provide an improved integrated air conditioning system for a bus.
Another object of the present invention is the provision for an integrated air conditioning system that does not occupy a significant portion of a luggage compartment on a bus.
Yet another object of the present invention is the provision in a bus for an air conditioning system whose performance is not significantly affected by the engine speed of a bus.
Yet another object of the present invention is an integrated bus air conditioning system which is economical to install and reliable in use.
Yet another object of the present invention is an integrated bus air conditioning system that is accessible and easy to service.
Still another object of the present invention is an integrated air conditioning system for a bus which is economical to manufacture and effective in use.
Another object of the present invention is that of providing a xe2x80x9climp homexe2x80x9d capability in the event of certain component failures.
These objects and other features and advantages become more readily apparent upon reference to the following descriptions when taken in conjunction with the appended drawings.
Briefly, in accordance with one aspect of the invention, a plurality of modules are placed under the floor of a passenger compartment of a bus, with each module having a complete air conditioning system which can be controlled independently of the speed of the engine.
By yet another aspect of the invention, each module has an invertor/controller which is interconnected to receive power for a generator and provide controlled AC power to the drive motors of a compressor and the condenser and evaporator blowers.
In accordance with another aspect of the invention, rather than a large single air conditioning unit, a plurality of relatively small identical modules can be installed on the roof of a bus, with each being capable of operating independently of the others so as to allow for the relatively low cost mass production of identical standardized units and also provide for a limp home capability in the event of failure of one or more units.
By yet another aspect of the invention a plurality of compact modules are slidably installed into or near a luggage compartment of a bus so as to facilitate easy access for servicing the units.
In accordance with another aspect of the invention, the modules are so designed that, when installed in their positions on the bus, their supply air outlet opening and return air inlet openings register with the existing supply air duct and return air duct on the bus.
In the drawings as hereinafter described, a preferred embodiment is depicted; however various other modifications and alternate constructions can be made thereto without departing from the true sprit and scope of the invention.